The operation of heavy mechanical equipment such as large tractors generates considerable heat in the engines of the equipment, which must be efficiently dissipated to prevent damage to the engine. This is generally accomplished by coolant-based radiator systems, in which a pump circulates coolant through tubes in a radiator. Air cools the tubes and, hence, the coolant, and the coolant is then pumped through various engine components, e.g., an engine oil cooler, to cool these components.
As recognized herein, many engines of heavy equipment are turbocharged. Turbochargers generate charge air for the engine which is used in the combustion process. To reduce engine emissions, the temperature of the charge air from the turbocharger should be minimized, and aftercoolers have been provided for this purpose. Coolant from the radiator can be used to cool the turbocharged air passing through an aftercooler.
Thus, it is important to minimize coolant temperature at normal operating conditions, both to effectively cool engine components and to reduce emissions in turbocharged engines. As recognized herein, however, it is further important to provide appropriate coolant flow rates at light loads, i.e., when the engine generates relatively little heat.
The above-referenced patent applications address both of these problems by providing multi-radiator, multi-pass dual circuit cooling systems. The present invention further understands that it is desirable and possible to better balance the heat load between heat removal circuits at low ambient temperatures and/or low engine heat Loads. Specifically, the present invention understands that it is desirable that the temperature of the coolant supplied to the aftercooler be relatively independent from the temperature of the coolant from the system thermostat during low temperature conditions.